1. Field
Embodiments relate to an apparatus for measuring skin moisture content and it's operation method. And more specifically it is about an apparatus for measuring skin moisture content and it's operation method which can prevent measurement errors that may occur when a current (C) electrode contacts with a user's skin before a reference (R) electrode, by measuring the user's skin moisture content only when a voltage at an output terminal of an operational amplifier is less than or equal to a value that is acquired by multiplying the voltage, which is supplied to a non-inverting input terminal of the operational amplifier by a predetermined constant.
2. Description of the Related Art
As many people become interested in beauty, an interest in skin care has also increased. A desire for a healthy skin affects not only beauty-related businesses, but also affects the growth of medical-related businesses since people need to protect their skin from ultraviolet rays that have become stronger due to the destruction of the ozone layer and various types of pollutions.
Skin is an organ of the integumentary system made up of multiple layers of epithelial tissues. Main functions of skin are protection against pathogens, harmful substances and the cold, waterproofing, temperature regulation, and the like. One of the most critical elements to enable the proper performance of the functions of skin is moisture content in a stratum corneum. Moisture content in the stratum corneum is generally referred to as skin moisture content. Maintaining proper moisture content in the stratum corneum enables the performing of basic functions of skin such as protection against harmful substances, and preventing excessive evaporation of skin moisture.
In view of skin care, skin moisture content is also considered as an essential element. Accordingly, fundamental to skin care is skin moisture management.
According to a conventional art, an electrical measurement method, an optical measurement method, and a method using a magnetic resonance imaging (MRI) are conventional methods of measuring skin moisture content. The electrical measurement method is widely used. More particularly, a method of measuring skin moisture content by measuring susceptance, i.e. an alternating current (AC) component of admittance of three electrodes, i.e. a reference (R) electrode, a current (C) electrode and a measuring (M) electrode, using a sinusoidal wave of low frequency is mainly used.
In the conventional method of measuring skin moisture content, measurement errors may occur in an order of contact by each electrode with the user's skin. Specifically, when the R electrode is the first electrode to contact with the user's skin and the C electrode subsequently contacts with the user's skin, skin moisture content may be measured by detecting a normal current signal from the user's skin via the M electrode.
However, when the C electrode contacts with the user's skin before the R electrode, noise may occur in the current signal detected via the M electrode due to a high voltage, which is supplied to the C electrode. Thus, the skin moisture content may not be accurately measured. Specifically, since noise may occur depending upon an order which a user contacts each electrode with the skin, the skin moisture content may not be accurately or consistently measured.
When noise occurs, often generating an error in measuring skin moisture content, a user may not make appropriate skin care choices, such as purchasing cosmetics unsuitable for the user's skin type based on an incorrect measurement value of skin moisture content, and the like.
Thus, an apparatus for measuring a user's skin moisture content accurately and consistently regardless of an order of contact by each electrode with the skin of the user, is required.